No — you do not have to use chlorine in a pool to keep it safe. What a pool needs is continuous disinfection, and chlorine is simply the most common way to provide it. UV, ozone and nanobubble oxidation all disinfect water without chlorine dosing, and a private pool, hotel pool or spa can run on any of them without ever adding chlorine. A Norwegian public pool is a different case: the regulation that governs it currently requires a measurable disinfectant residual in the water, so the realistic outcome there is strongly reduced chlorine, not zero.
What Does Chlorine Actually Do in the Water?
Chlorine's job is disinfection: it oxidises pathogens and organic matter fast enough to keep ahead of what bathers bring into the water — skin cells, sweat, cosmetics, urine. The problem is not chlorine itself; it is what chlorine turns into once it has done that job. Combined with nitrogen compounds from bathers, free chlorine becomes chloramines, the actual source of the sharp smell and stinging eyes people usually blame on “too much chlorine” — it is almost always the opposite.
So the real question behind “do you have to use chlorine in a pool” is narrower than it sounds. Does the water need continuous oxidative disinfection? Yes, always. Does that disinfection have to come from chlorine specifically? No.
What Are the Alternatives to Chlorine in a Pool?
Three approaches come up repeatedly once a facility manager starts comparing suppliers:
- UV disinfection. Inactivates pathogens as water passes under a UV lamp in the circulation loop. It leaves no residual on its own, so it is usually paired with a small amount of chlorine or another oxidant.
- Salt chlorination. Generates chlorine electrolytically from dissolved salt. It is still a chlorine system — the water still carries free chlorine and can still form chloramines — just dosed differently. See what a salt chlorinator actually does to your water over a season for the detail.
- Nanobubble oxidation. NanoSWIM's systems inject oxygen or ozone as bubbles under roughly 200 nanometres across — small enough that buoyancy stops dominating, so they stay suspended in the water for days rather than rising and bursting in seconds. Bubble collapse releases concentrated oxidative energy that disinfects and breaks down organic load without chlorine dosing.
Coarse ozone injection is also common, but most of the gas escapes at the surface before it can react. The very large combined surface area of a nanobubble is what makes the oxidation more complete — the mechanism is explained in more depth here.
Can a Pool Really Go Fully Chlorine-Free?
Private pools, hotel pools and spas can. Once there is no regulatory requirement for a measurable chlorine residual, nanobubble oxygen or ozone treatment can carry the full disinfection load on its own, running inline in the existing circulation loop after filtration — no separate contact tank, no chemical delivery, no chlorine smell in the plant room. See what a chlorine-free pool actually involves for what changes and what does not.
A Norwegian public pool cannot go that far today. Forskrift om badeanlegg, bassengbad og badstu, enforced by the municipal health authority, requires bathing water to carry a measurable disinfectant residual, and Folkehelseinstituttet's guidance sits on top of that. A public facility can still cut chlorine dosing sharply by handling most of the oxidative load with nanobubbles and topping up the residual conventionally; it just cannot remove chlorine entirely and still meet the regulation as it stands today.
That distinction is worth being blunt about, because it is the honest limit of the technology. Nanobubble treatment is a treatment-loop system, exactly like UV and ozone injection — it acts on water passing through the plant room, not something poured into the basin, and it does not replace correct filtration, sensible pH control or competent operation. Capital cost is also higher than a dosing pump and a drum of chemical, which is worth weighing against what the facility is actually trying to solve.
Chlorine vs. the Alternatives, at a Glance
| Method | Leaves a chlorine residual? | Works in the circulation loop? | Realistic for a Norwegian public pool? |
|---|---|---|---|
| Standard chlorine dosing | Yes | No — dosed into the basin or a balance tank | Yes, and currently required |
| Salt chlorination | Yes — it is still chlorine | Partially — generation is inline, chlorine still enters the basin | Yes |
| UV disinfection | No, on its own | Yes | Only combined with a chlorine source |
| Nanobubble oxygen/ozone (NanoSWIM Pool System) | No | Yes, after filtration | Reduces dosing sharply; does not remove the residual requirement |
How Much Can Chlorine Use Actually Be Reduced?
Against a conventional chlorine dosing regime on comparable pools, NanoSWIM's figures show up to 90% less chemical use, with 99.9% pathogen reduction from the oxidative disinfection running in the treatment loop. The clearest documented result is a 2,500 m² resort pool complex in southern Europe — the client is not named, for commercial confidentiality — that saw 85% less chlorine consumption and 60% lower water-treatment operating cost, which is the treatment line specifically, not the resort's total running cost. There is no published price or payback period for any of this. The honest answer to “what would this cost us” is to bring your own pool volume and flow rate and ask for a number against your actual site.
What Should You Check Before Deciding?
- Is this a public facility subject to forskrift om badeanlegg, bassengbad og badstu, or a private pool, hotel pool or spa with no residual requirement?
- What is the pool's flow rate and volume, and does it fall inside a treatment system's rated capacity?
- Does the plant room have the space and circulation-loop access a treatment-loop system needs?
- Is a supplier claiming a specific certificate or approval — and can they show it, or are they only describing a mechanism? See the full comparison against conventional chlorine dosing before taking any supplier's word for it, including NanoSWIM's.
In my own experience, the question that tells me whether a Norwegian buyer is serious comes long before we ever get to the tank or the flow rate — it's when they ask how the system logs its own operation, not whether it works. I've had a facility's driftsansvarlig want to see a sample logbook before we'd even talked through their pool volume, which almost never happens with a buyer from outside Norway at the same stage of a call. It changed how I open these conversations now — I bring the documentation question up myself before anyone has to ask it.
If you are weighing chlorine against an alternative for your own facility, get in touch with NanoSWIM and we can look at what is realistic for your pool volume, flow rate and regulatory situation.